Name:	ibm_DefinedBenefitPlanPeriodUsedInFinalPayFormulaThatDeterminesBenefits
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Defined Contribution Plan, Company Monthly Contributions to Retirement Benefit Accounts (RBA) Based on Employee Eligible Compensation, Percent

No definition available.

Name:	ibm_DefinedContributionPlanCompanyMonthlyContributionsPercent
Namespace Prefix:	ibm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

First level of employer's automatic contribution to a defined contribution plan, expressed as a percentage of employees' eligible compensation, based on eligibility to participate in the plan as of a specified date.

No definition available.

Name:	ibm_DefinedContributionPlanEmployerAutomaticContributionPercentLevelOne
Namespace Prefix:	ibm_
Data Type:	dtr-types1:percentItemType
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Third level of employer's automatic contribution to a defined contribution plan, expressed as a percentage of employees' eligible compensation, based on eligibility to participate in the plan as of a specified date.

No definition available.

Name:	ibm_DefinedContributionPlanEmployerAutomaticContributionPercentLevelThree
Namespace Prefix:	ibm_
Data Type:	dtr-types1:percentItemType
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Second level of employer's automatic contribution to a defined contribution plan, expressed as a percentage of employees' eligible compensation, based on eligibility to participate in the plan as of a specified date.

No definition available.

Name:	ibm_DefinedContributionPlanEmployerAutomaticContributionPercentLevelTwo
Namespace Prefix:	ibm_
Data Type:	dtr-types1:percentItemType
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First level of percentage of employees' eligible compensation for which the employer contributes a matching contribution to a defined contribution plan for employees hired prior to a specified date.

No definition available.

Name:	ibm_DefinedContributionPlanEmployerMatchingContributionPercentLevelOne
Namespace Prefix:	ibm_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

Second level of percentage of employees' eligible compensation for which the employer contributes a matching contribution to a defined contribution plan for employees hired prior to a specified date.

No definition available.

Name:	ibm_DefinedContributionPlanEmployerMatchingContributionPercentLevelTwo
Namespace Prefix:	ibm_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

The minimum service period after which employees receive automatic contributions and matching contributions to a defined contribution plan.

No definition available.

Name:	ibm_DefinedContributionPlanMinimumServicePeriodAfterWhichEmployeesAreEligibleToReceiveContributions
Namespace Prefix:	ibm_
Data Type:	xbrli:durationItemType
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
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Name:	us-gaap_RetirementPlanNameAxis=ibm_IBM401kPlusPlanMember
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Name:	us-gaap_RetirementPlanNameAxis=ibm_IBMExcess401kPlusPlanMember
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Name:	us-gaap_RetirementPlanTaxStatusAxis=us-gaap_NonqualifiedPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_RetirementPlanTaxStatusAxis=us-gaap_QualifiedPlanMember
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Data Type:	na
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Name:	us-gaap_RetirementPlanSponsorLocationAxis=country_US
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Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
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